1. Field of the Invention
The present invention relates to a method for producing a three-dimensionally shaped aromatic imide polymer sheet article. More particularly, the present invention relates to a method for producing a three-dimensionally shaped article having at least one convexity or concavity from an aromatic imide polymer sheet.
2. Description of the Related Arts
It is known that an aromatic imide polymer exhibits an excellent heat resistance and superior chemical and physical properties and, therefore, is useful as a resinous material to be employed under severe conditions, and there are a number of studies underway into the utilization of various aromatic imide polymers.
It is also known that most of the known aromatic imide polymers are employed in the form of a flat sheet or film, and it is very difficult to form a three-dimensional shape from the aromatic imide polymer sheet, because of a poor formability thereof. That is, a method for industrially producing three-dimensionally shaped articles, for example, various forms of cups or containers, from the aromatic imide polymer sheet, has not been known.
The above-mentioned problem has arisen because most of the conventional aromatic imide polymers substantially do not have a satisfactory thermoplastic property, when compared to ordinary thermoplastic polymers, and therefore, it is practically impossible not only to directly mold the conventional aromatic imide polymers by means of a usual extrusion forming or injection forming method into a desired form of an article, for example, a container, but also to shape sheets or films of the conventional aromatic imide polymers by means of a conventional sheet-shaping method.
Various industries wish to utilize the aromatic imide polymers, which exhibit an excellent heat resistance and chemical resistance, to provide heat and chemical resistant articles, for example, protective containers and protective covers for electric and electronic parts and electric and electronic devices which are subjected to heat treatments and/or chemical treatments. But, due to their poor formability, most of the conventional aromatic imide polymer sheets cannot be shaped into three-dimensionally shaped articles having a desired convexity or concavity and usable as containers or covers, with an industrially satisfactory efficiency.
Before the present invention, it has not been known how to industrially produce a three-dimensionally shaped aromatic imide polymer article, for example, a container or cover, from an aromatic imide polymer sheet having an excellent heat resistance and desirable chemical and physical properties.